Question

37 the diagram below shows an energy pyramid for an aquatic ecosystem. top carnivores carnivores herbivores producers which of the following statements best explains why the energy pyramid is narrowest at the top? a the organisms at the top of the pyramid need only a small amount of energy for their metabolism. b the organisms at the top of the pyramid receive only a small fraction of the energy that originally enters the system. c the organisms at the top of the pyramid are the most efficient feeders. d the organisms at the top of the pyramid have the largest population sizes.

Explanation:

To solve this, we analyze each option:

• Option A: Top - level organisms (e.g., large fish) have high metabolic needs, so this is incorrect.
• Option B: In an energy pyramid, energy transfer between trophic levels is inefficient (only ~10% transferred). So, top - level organisms (top carnivores) receive a small fraction of the initial energy (from producers), which explains the narrow top (less energy available, so fewer organisms or less biomass). This is correct.
• Option C: Energy transfer inefficiency is due to energy used in metabolism, not feeding efficiency. So this is incorrect.
• Option D: Top - level organisms usually have smaller population sizes (narrow pyramid), so this is incorrect.

Answer:

B. The organisms at the top of the pyramid receive only a small fraction of the energy that originally enters the system.